Punch assembly for film products with work clamping means

Abstract

Punching apparatus particularly adapted for use in connection with flexible film materials including cooperatively arranged punch and die assemblies arranged in aligned relationship, and ram means for reciprocably driving or stroking the punch assembly in a reciprocatory path into engagement with the work film and die for performing cutting or perforating operations on the film. A film clamping shoe is provided on the punch and is disposed in opposed relationship to the die assembly, the shoe being arranged to clampably engage the work film disposed between the punch and the die upon advancing or stroking motion of the punch. An annular flange extends upwardly from the surface of the die and toward the punch and film clamping shoe means so as to provide for taut engagement and retension of the film by the film clamping shoe means.

I claim as my invention: 
     
       1. In a punch assembly for perforation of flexible film products with cooperatively arranged punch and die assemblies, and comprising: a. frame means for retaining a reciprocating punch and a stationary die;   b. a punch assembly including a punch member mounted on said frame means and including drive means for stroking said punch member in reciprocatory to-and-fro motion along a certain linear path of a first predetermined length and having upper and lower linear path limits;   c. a die assembly mounted on said frame means and including die and die base means with a punch-receiving bore formed therein and with said die and die base means having a film supporting upper pad surface circumscribing said die bore;   d. film clamping shoe means with a film clamping lower surface in opposed relationship to said film supporting upper pad surface and being slidably secured to said punch member with resilient coupling means and adapted to move with said punch member along the upper portion only of said linear path, said film clamping shoe means being secured to said punch member at an elevation normally spaced from said film supporting upper surface a second predetermined length which is less than said first predetermined length;   e. resilient means normally biasing said film clamping shoe toward said film supporting upper surface and arranging for compressive engagement of flexible film between said film supporting upper surface and said film clamping surface upon driving of said punch means toward said die a stroke length at least equal to said second predetermined distance; and   f. flange means being disposed along said film supporting upper surface extending radially outwardly from the edge of said bore and in circumscribing relationship to said die bore, and wherein the upper edge surface of said flange is spaced upwardly from said film supporting upper surface and terminates radially inwardly of the inner edge surface of the film clamping lower surface of said clamping shoe.   
     
     
       2. The punch assembly as defined in claim 1 being particularly characterized in that said resilient means normally biasing said film clamping shoe is a resilient spring member. 
     
     
       3. The punch assembly as defined in claim 2 being particularly characterized in that a pair of resilient spring members are disposed in oppositely disposed relationship across said punch member. 
     
     
       4. The punch assembly as defined in claim 1 being particularly characterized in that said drive means is a fluid operated cylinder. 
     
     
       5. The punch assembly as defined in claim 4 being particularly characterized in that said drive means is a gaseous fluid operated cylinder. 
     
     
       6. The punch assembly as defined in claim 1 being particularly characterized in that means are provided for delivering a pulse of compressed air to said punch for ejecting film slugs from said punch member. 
     
     
       7. The punch assembly as defined in claim 1 being particularly characterized in that said film clamping surface is arranged in circumscribed relationship to said flange means, with the inner periphery of said film clamping surface being spaced outwardly from the outer surface of said flange means so as to define an annulus therebetween.